Microbio

Question 1

In general parasitic worms are not very virulent and produce subacute to chronic infections. How is this possible and when are they typically detected?

why are they difficult to treat?

Answer 1

They have immune evasion strategies, and severity often is related to infectious dose acquired over time; repeat exposure.

Intracellular, eukaryotic, unsanitary conditions leads to re-exposure, complex life cycles.

Question 2

What is an example of a cestode, nematode, or trematode? All are classified as what?

Answer 2

cestode-tapeworm
nematode-roundworm (nice and round)
trematode-flukes (flat and fleshy)

Question 3

What are the characteristics of worms in intermediate and definitive hosts?

Answer 3

Intermediate larvae (asexual repro)

Definitive-Done/adults have sex

Question 4

What is di-phill-o-both-rium latum? How does it absorb nutrients? Describe it.

Answer 4

cestode/tapeworm that can absorb nutriens through cuticle b/c it lack as digestive system.

Head is a scolex not a rolex
Eggs shead by proglottids (gravid proglottids) a million a day
Host life cycle-freshwater crustacean, freshwater fish that eats them, Fish eating mammal (us)

Question 5

What are the characteristics of nematodes/roundworms? What an example of a nematode?

Answer 5

nonsegmented, tapered at both ends
have a digestive system

Enterobius vermicularis/pinworm: most common helminth infection in the US. Scotch tape test. Anal pruritis is most common symptom.

Question 6

what is the definitive and intermediate host of a pinworm? how are they transmitted?

Answer 6

humans for both.

Transmission-the worms are light and can be released when the anus is scratched. They can then go into the air and land on objects. Spread well in preschools.

Question 7

Name a fluke that infects the bile ducts and liver. describe it.

Answer 7

opisthorchis sinensis/clonorchis
fluke/trematode

unsegmented, leaf shaped, hermaphroditic (except schistosoma), 2 intermediate hosts (except schistosoma) , all have snails as first intermediate host.

Usually asian, infects carnivores, life span 20-30 yrs
1st freshwater snail, 2nd freshwater fish 3 human. Like H.pylori its a class 1 carcinogen.

Question 8

What’s the hatch on a liver fluke called?

Answer 8

operculum

Question 9

What are the clinical features of opisthorchis sinensis?

Answer 9

Inflammation and intermittent obstruction of biliary duct
acute: abdominal pain, nausea, diarrhea, esosinophils
Chronic: fatigue, anorexia, jaundice, secondary infection, and cholangiocarcinoma